The present invention relates to a device for covering a trunk of a motor vehicle, in particular to a device comprising a trunk lid movable relative to a body of the vehicle, a force transmission unit for driving the movement of the trunk lid, and a fastening means for releasably securing the trunk lid in a closed state of the trunk lid.
In modern-day automotive construction, especially the building of convertibles, there is an increasing call for automatic swing-open cover elements to be provided for the body. Of particular importance in this regard is a simple and robust construction which can be cheaply produced in large batch quantities and works reliably over a long service life.
German patent DE 199 10 763 C1 describes a device for opening and closing a tailgate, in which the tailgate can be swiveled open and shut by means of a hydraulic cylinder, the hydraulic cylinder being mounted over a long hole, so that a pickoff of a movement of the hydraulic cylinder in the long hole by means of Bowden cables is used to actuate a lock of the tailgate, indirectly through the hydraulic cylinder. Such a mechanism is not very robust, is complex and is prone to breakdown, at least over a long service life.
DE 299 16 003 U1 describes as fastening means of a trunk cover for a motor vehicle a lock element having a catch hook which, in a closed position of the cover configured as a lid part, embraces a bolt fixed to the body and, in this way, releasably secures the lid part. The catch hook is actuated by a pull-and-push linkage, which acts upon a lever close to the catch hook in order to rotate the catch hook about its axis. The linkage thus acts with the lever in the style of a link rod for the fastening means. The linkage is drive-connected by means of a bolt guided in a keyhole connecting link and forming the end region of a piston rod of a force transmission unit configured as a drive means. However, the drive does not act directly upon the linkage, but only indirectly, via the guidance of the bolt in the long hole of the keyhole connecting link. A drawback is that the coupling between the force transmission unit and the fastening means comprises a large number of individual parts. Also disadvantageous is the fact that the guidance of the bolt in the long hole of the keyhole connecting link is susceptible to wear and prone to noise generation. Another drawback is that forces which act upon the lid part from outside are conveyed directly to the force transmission unit and can damage this. The described coupling between the force transmission unit and the fasting means comprises a lot of single elements and is applicable only for specific configuration, which renders an upgrading of arbitrary trunk lids difficult to accomplish. Referred to as a further lock is a keyhole connecting link having a neck region and a widened head region in which the bolt of the piston rod of the drive member is guided, which keyhole connecting link cannot be used to secure the lid part releasably to the body.
German utility model DE 299 16 002 U1 describes a trunk lid, configured as a lid part, for covering a trunk of a motor vehicle, the lid part being able to be brought, by means of a force transmission unit configured as a drive member, especially by means of a hydraulic cylinder, into two different opening positions, a multi-bar arrangement having four parts, especially four links of a four-bar mechanism, being assigned to a front end region of the lid part. For the securement of the lid part, a locking element is provided, which is configured as a mechanical lock integrated into the hydraulic cylinder. The lock integrated into the hydraulic cylinder is not, however, connected to the lock by a link connection. A drawback with this is that external forces acting upon the secured lid part are transmitted directly to the hydraulic cylinder and can hence damage the mechanism as a whole or the hydraulic cylinder. A lock which is configured in the style of a pivot latch and is operatively connected to the drive member secures the four parts, especially the four mutually coupled links of a multi-bar mechanism, in order to allow a first open position. The lock is not designed to secure the lid part on the body, since the lid part can be opened even when the lock is closed.
German patent application DE 36 26 747 A1 describes, as a baggage compartment cover being used as a trunk lid, which can be secured to a body by means of a fastening means, the fastening means comprising a body-fixed closing part, the web of which is gripped by a fork-like companion closing part fastened to the baggage compartment cover. A force transmission unit is formed as a piston rod of a push-out tool configured as a hydraulic cylinder. The push-out tool acts via a continuation and a bearing journal directly upon a two-armed clamping lever, the U-shaped end of which forms the companion closing part. Between the fastening means and the force transmission unit, a direct action of the force transmission unit both upon the fastening means and upon the trunk lid is possible without the need for a link gear mechanism.
German patent DE 195 16 876 C1 describes a supporting frame configured as a trunk lid, which can be transferred by means of a drive of a force transmission unit, which drive is configured as a hydraulic cylinder, into a fastening position in which the supporting frame can be releasably secured by means of a fastening means configured as a snap fastening, which comprises a pivot latch fastening and a fastening stud part cooperating therewith. The hydraulic cylinder acts directly upon the supporting frame, a cable pull being provided at a foot of the hydraulic cylinder as a coupling with a trip lever of the pivot latch fastening. A cable pull is provided as a connection between the fastening means and the force transmission unit. A drawback with the cable pull is that this is not very robust and is susceptible to wear in the course of lengthy operation. The foot of the hydraulic cylinder is guided by means of a bolt in a long hole, whereby the cable pull is attached to the bolt. When the hydraulic cylinder is actuated, first the bolt is shifted along the long hole to one end thereof and is fixed by spring elements at the first end of the long hole. In a second step, upon further linear movement of the piston rod of the hydraulic cylinder, the trunk lid can be moved. It is a drawback that a portion of the movement of the hydraulic cylinder is need to merely actuate the locking means, which necessitates that a comparatively long hydraulic cylinder has to be provided. As a further drawback, a voluminous hydraulic cylinder has to be used. Furthermore, it is not ensured that forced acting on the trunk lid are transmitted to the hydraulic cylinder. It is a still further disadvantage, that the hydraulic cylinder is secured only be means of the spring elements; as a consequence, the arrangement is prone to malfunction. Finally, the arrangement comprises a multitude of elements and requires a long hole, rendering the arrangement difficult to upgrade for a given trunk lid.